Why is SEPA Direct Debit not visible as payment method?

The donor can't choose to pay via SEPA Direct Debit for recurring payments. This will happen automatically on the background when you have enabled recurring payments in the plugin.

If the donor has for a recurring donation, the first payment will go via another payment method like iDEAL or Bancontact. For all supported payment methods, you can read this support article from Mollie.

After the first payment, a subscription is started so Mollie will automatically debit the recurring payments via a SEPA Direct Debit.